Mathematical model of solid-state diffusion at periodic plastic deformation

A new mathematical model of enhanced solid-state diffusion in binary metallic systems under the action of intensive periodic plastic deformation is developed with reference to mechanical alloying. The generation of non-equilibrium point defects (vacancies and interstitial atoms) due to the shear deformation, their relaxation during the intervals between collisions, the increase of diffusion coefficients, and cross-term effects are considered. Modelling is performed using both the realistic values of self-diffusion coefficients for substitutional alloys and the characteristics of a milling device, which determine,the intensity and periodicity of deformation. The physical mechanism of a substantial acceleration of diffusion is determined.